Contemporary vehicles include various braking systems that enable the operator to stop the vehicle by applying pressure to a brake pedal. Vehicle braking assemblies include a pedal with arm connected to the braking system. A power booster can be positioned with respect to the pedal arm; the power booster amplifies the braking force provided by the pedal arm. It is standard to include a clevis pin connected to the pedal arm and a clevis attached to the pedal booster. The clevis assembly guides the pedal arm into alignment and with engagement with the power booster. Conventional hybrid electric vehicles include by-wire braking assemblies having clevis assemblies. Such assemblies, however, can be very complex to install. Moreover, the parts for the clevis assembly can increase the end-item part costs for the vehicle braking assembly.
U.S. Patent Application Publication No. 20070193394—for example—discloses a push rod bracket assembly that includes a booster clevis having a pushrod support wall, with a booster push rod extending outward therefrom into engagement with the booster assembly. Extending away from the pushrod support wall are two legs, a retainer clevis leg and a slotted clevis leg. The retainer clevis leg mounts on a first side of the brake pedal arm and includes a pin hole that aligns with the bracket attachment hole. This assembly still requires the basic components of a clevis assembly which can be costly to produce and install.
Existing attempts to remove the clevis assembly from the braking system require parts that are similarly complicated. For example, U.S. Pat. No. 7,409,889 discloses an arrangement in which an end of a booster control rod has a head and a spherical bearing surface is housed in a complementary boss formed in a wall of the intermediate part of the booster actuating bar. A retaining pin is used to couple the booster rod to the pedal arm. Though this assembly does not require a traditional clevis, the assembly is complicated and adds production and manufacturing costs to the vehicle as well.
Therefore, it is desirable to reduce part complexity for the braking assembly by reducing the number of end-item parts to the plant. It is beneficial to provide a simpler engagement between the power booster rod and brake pedal arm to reduce the production and manufacturing costs of the vehicle.
Other considerations also come into play when designing a by-wire vehicle braking system. In vehicles having regenerative braking systems there can be a gap defined between the brake pedal arm and hydraulic booster interface to allow for at least some of the rotational energy in the wheels to be harvested. This gap can be of larger or smaller sizes to accommodate different vehicle specifications. Where there is a failure in the by-wire braking system, the gap is undesirable and can unnecessarily delay the application of the hydraulic braking system. In by-wire braking systems that decouple the brake pedal from the active booster the gap between the booster and the pedal needs to be overcome if the system is no longer able to operate in by-wire mode. The resulting brake pedal travel is undesirable.
It is also desirable to provide a gap management device for a by-wire braking system. It would be beneficial to have a brake pedal assembly in which the spacing between the pedal arm and power booster can be adjusted for different vehicle conditions. In the case of by-wire system failure, it is desirable to have a braking assembly that closes the spacing between the pedal arm and the hydraulic booster interface.